Selection from Gonococci Grown in vitro of a Colony Type with some Virulence Properties of Organisms Adapted in vivo

Abstract

S U M M A R YGonococci from subcutaneously implanted chambers in guinea pigs produced, on agar, more than 95 % small colonies showing a 'double highlight' (DH) effect in oblique reflected light combined with transmitted light. Laboratory strains of gonococci produced some DH colonies, but others showed a single highlight (SH) or no highlight (NH). Selection of DH colonies and comparison of their organisms with gonococci grown in vivo and with those from SH colonies, showed that the DH character was associated with high infectivity for guinea-pig chambers, resistance to killing by human phagocytes and heavy pilation. Furthermore, DH colonies were found in the first culture of three fresh samples of urethral pus. Thus, the DH colony characteristic may be a more reliable criterion of pathogenicity of gonococcal isolates than systems used previously. There were, however, some differences between the gonococci grown in vivo and the DH colony types. The gonococci grown in vivo and cultured once on solid medium possessed one or two antigens which differed from those of DH (or SH) colonies. They also formed smooth suspensions (which separated slowly) in saline, compared with the rough suspensions (which separated quickly) formed by gonococci from DH (or SH) colonies. Finally, the organisms grown in vivo were resistant to killing by human serum whereas the DH (and SH) colony types were susceptible; the resistance of the organisms grown in vivo was lost during one subculture on agar suggesting that the property is a phenotypic characteristic. Hence, in addition to selecting DH colony types the conditions in vivo produce organisms which differ, probably phenotypically, from cultured organisms.

The Effect of Specific Antiserum on the Resistance of Neisseria gonorrhoeae to Intracellular Killing by Phagocytes of Human Blood

“…In two experiments, the resistance of strain BSSH, which was lower than that of strain BSDH in the absence of antiserum (Penn et al, 1977b), was further reduced by the addition of antiserum to strain BS.…”

“…Subsequently, strain BS was shown to contain at least two different types of organisms. The majority, designated BSSH, formed colonies which exhibited a ' single highlight' (SH) morphology when examined under the lighting conditions described by Penn, Veale & Smith (1977b). The others, designated BSDH, formed colonies with a 'double highlight' (DH) morphology like that of the organisms adapted to growth in guinea-pig chambers.…”

“…The effect of antiserum could be neutralized by adsorption with intact organisms or with extracts, prepared ultrasonically, of the homologous strain. Antiserum also promoted the intracellular killing of a strain which had a 'single highlight' colonial morphology (Penn et al, 1977b) and a low natural resistance to phagocytic killing, but adsorption with this strain neutralized the antiserum less consistently than the DH strain. The neutralization of antiserum-mediated promotion of intracellular killing by extracts of organisms naturally resistant to such killing may provide an assay for the aggressins responsible for this resistance.…”

The Intracellular Survival and Growth of Gonococci in Human Phagocytes

“…Growth of strain BS in subcutaneous chambers in guinea pigs selected organisms with a greater resistance to killing by phagocytes (Witt et al, 1976a). Similarly resistant organisms could be selected in vitro by their 'double highlight' (DH) colonial morphology (Penn et al, 1977). Drutz (1978) used the incorporation of radioactively labelled adenine to indicate intracellular metabolic activity of gonococci in infected human PMN phagocytes treated with rat serum to kill extracellular organisms.…”

SHORT COMMUNICATION Induction of Phenotypically Determined Resistance of Neisseria gonorrhoeae to Human Serum by Factors in Human Serum

“…The serum resistance was of two types. Gonococci from disseminated gonorrhoea and some of the strains from urethral exudates and guinea pig chambers exhibited a resistance which was retained on subculture in vitro (Schoolnik et al, 1976;Ward et al, 1970;Penn et al, 1977). The second type of resistance, in which we are interested, was lost on subculture in vitro and was shown by most of the strains from urethral exudates (Ward et al, 1970) and guinea pig chambers (Penn et al, 1977).…”